1. Field of the Invention
The present invention relates to a key assembly for a mobile terminal, and a mobile terminal having the same.
2. Description of Related Art
A mobile terminal is one of many portable electronic devices capable of enabling a user to wirelessly transmit/receive data or to process information while being moved. As the mobile terminal becomes lighter and slimmer in order for the user to conveniently carry it, the mobile terminal requires a mechanical structure to implement various functions in a small and limited device.
Generally, the mobile terminal is provided with a key assembly having a plurality of key buttons to input numbers, characters, and other control commands by the user. FIG. 1 is a sectional view showing a key assembly in accordance with the related art. As shown, the related art key assembly 1 comprises a plurality of key buttons 2 exposed outside the mobile terminal and is pressably-operated. A switch 6 is arranged below the key buttons 2 and is mounted on an upper surface of a circuit board 4, for receiving a signal as the key buttons 2 are pressed. A pad 3 is attached to a lower surface of the key buttons 2 and is elastically transformed when the key buttons 2 are pressed, for pressurizing the switch 6 to thereby input a signal. A pressurizing protrusion 7 for pressurizing the switch 6 as the key buttons 2 are pressed is disposed at the pad 3.
The key buttons 2 are arranged on a case 9 so as to be outwardly exposed, and have symbols such as numbers, characters, or other command prompts, on the upper surfaces of the key buttons 2. The symbols are printed as a negative type to selectively pass light generated from light emitting diodes (LEDs) 5, which will be explained later, thereby implementing a backlighting of the symbols.
When a user pushes the key buttons 2, the pressurizing protrusion 7 of the pad 3 is pressed against switch 6. Accordingly, the user can input the desired keys.
A plurality of LEDs 5 for illuminating the key buttons 2 are upwardly protruding near the switches 6 of the circuit board 4. The symbols on the key buttons 2 are illuminated by the LEDs 5, so that the user can input the symbols even in a dark place.
However, in the related key assembly art, light is not uniformly distributed because of the distance between the LEDs 5 and the key buttons 2. Furthermore, in order to enhance the brightness of the key buttons 2, the number of the LEDs 5 have to be increased, thereby requiring a larger power consumption.
In order to solve the above problems, the Korean Patent Publication No. 10-2003-89182 discloses a technique for arranging a light guiding plate on an upper surface of a main board having dome switches, the light guiding plate having passing holes in correspondence with the dome switches.
However, in the Korean Patent Publication No. 10-2003-89182, the number of the passing holes corresponds to the number of the dome switches, thereby requiring a difficult processing operation. Furthermore, a large amount of light disappears in the light guiding plate, thereby not sufficiently illuminating each of the key buttons.
Korean Patent Publication No. 10-2005-64351 discloses a technique that a light guiding plate is attached to a lower surface of a keypad and a light emitting device is mounted on an additional circuit board attached to the light guiding plate. However, since the light emitting device is installed separately from the main board, an additional structure for fixing the light emitting device and an electric connection unit are required. Accordingly, an entire process is complicated and a fabrication cost is increased.